The Senate majority leader and the speaker have never been especially close, but their normally functional relationship began to unravel this week, after the House GOP decided to try to undermine a secret deal the two leaders’ offices made over the summer to save congressional staffers from losing their health care benefits.

With the government currently shut down and only 17 days until the Treasury runs out of money to pay the nation’s debts, the strained relationship could bode ill for a swift political resolution.

But sources say Reid and his chief of staff, David Krone, were so angry with the Ohio Republican that they decided to breach accepted protocols between the two offices after Boehner’s Monday decision to add a provision to a stopgap spending bill that would eliminate employer health care contributions for members and staff.

Though leaders usually refrain from referring to each other in their partisan rants against the other chamber, Democratic leaders on Monday mentioned Boehner by name 12 times. It was a noticeable shift from previous shutdown debates when Reid and Democratic messaging lieutenant Charles E. Schumer of New York focused much of their political venom on No. 2 House Republican Eric Cantor or the tea party wing of the GOP.

“I have a very simple message to John Boehner: Let the House vote. Stop trying to force a government shutdown. Let the House work its will, all 435 members, not just the majority,” Reid declared in one of his multiple speeches Tuesday. “If John Boehner blocks this, he will be forcing a government shutdown, and it will be a Republican government shutdown, that’s pure and simple.”

The Nevada Democrat’s camp decided to leak a private email exchange between Krone and Boehner Chief of Staff Mike Sommers. The disclosure of the emails was designed largely to embarrass Boehner for publicly advocating to get rid of what Republicans have called a “special exemption” in Obamcare for lawmakers and staff. The existence of the emails, and Democrats’ plans to use them against Boehner, was first reported by Roll Call.

The communications, leaked to Politico, reveal that Sommers’ and Krone’s coordinated attempts to convince the Obama administration to preserve health care benefits for the thousands of staffers on Capitol Hill.

Dating back to a meeting with Reid, Boehner, Krone and then-chief of staff Barry Jackson when the GOP took control of the House in 2011, top aides to the two leaders have been under specific orders to work together. Krone and Jackson might have had a closer relationship — in large part because they worked to avoid a shutdown in April 2011 — but Sommers and Krone also had a good working relationship prior to the email leak, sources in both parties and chambers said.

The Reid-Boehner relationship has had its rocky moments in the past — notably late last year amid the fiscal-cliff negotiations when Reid had been calling Boehner a “dictator” on the floor and the speaker told Reid in person, “Go f--- yourself.”

This time around, Reid and Krone were already upset that Boehner continued his push to include Obamacare policy riders on the continuing resolution fight so close to a government shutdown.

“This basic thing is — once he feels you back out of your word, he loses all respect and it’s difficult for him to engage,” said one source familiar with Reid’s thinking.

This source added that Reid believed Boehner “would not let the government shut down and that at some point he would be reasonable. ... He promised he would not use health care on the shutdown.”

Attaching an amendment that would revoke staff health care subsidies to the continuing resolution was the last straw for Reid. He saw the move as intended to put vulnerable Senate Democrats in a tough spot and thought it represented a broken agreement between the leaders.

“If Republican senators believe they should bear the full cost of their health insurance, they should decline the employer contribution and pay their own way. They should stop being hypocritical. They should practice what they preach,” Reid said on the floor Monday. “Punishing 16,000 innocent congressional workers is simply mean-spirited. Speaker Boehner knows this new amendment won’t last longer than the last one when it gets to the Senate.”

Boehner spokesman Michael Steel, however, disputed the notion that Boehner had broken his word to Reid by including Obamacare amendments to the CR. “There was never any such promise from the speaker to Sen. Reid,” Steel said.

When asked what the email leak said about the state of the Reid-Boehner relationship, another Democratic source said, “It kind of speaks for itself.”

But the source questioned the wisdom of disclosing the emails and breaking unwritten rules about private communications between the leaders’ offices, asking, “What purpose does this serve except to denigrate the relationship?”

Reid and Boehner will likely have to try to talk at some point about how to reopen the government and avert a debt default. But several sources speculated that Reid’s anger at Boehner is such that he is inclined to wait out the shutdown just long enough to force other Republicans, such as Minority Leader Mitch McConnell, R-Ky., to get involved.